FIG. 16 is a sectional view of a conventional refrigerator disclosed in Japanese Laid-open Patent No. H8-54172. A refrigerator main body 1 comprises a freezing compartment 2, a refrigerating compartment 3, and a cooling section 20. The cooling section 20 incorporates an evaporator 10 cooled by circulation of refrigerant, and a defrosting heater 15 having a Nichrome wire coil covered with a glass tube.
A fan 11 sucks air into the cooling section 20 from the freezing compartment 2 and refrigerating compartment 3 through a freezing compartment suction port 7 and a refrigerating compartment suction port 8 for cooling the air by exchanging heat with the evaporator 10. The fan 11 sends the cooled air into the freezing compartment 2 through a diffusion port 9. The cooled air is also distributed into the refrigerating compartment 3 from the freezing compartment 2 through the passage not shown. When the air sucked into the cooling section 20 exchanges heat with the evaporator 10, the moisture in the air is frosted and sticks to the evaporator 10.
Before the frost deposit begins to lower the cooling capacity of the refrigerator, the frost is thawed by applying current to the Nichrome wire of the defrosting heater 15. As the Nichrome wire is energized, heat rays are emitted from the Nichrome wire to the evaporator 10 and peripheral parts through the glass tube. Heat rays emitted to a bottom plate 17 are reflected to peripheral parts including the evaporator 10 and defrosting heater 15. Heat rays thaw the frost deposits on the evaporator 10, a gutter 13 and drain port 14. A roof 16 is provided to protect the defrosting heater 15 from thawing water. The thawing water drops into the gutter 13, and discharged outside of the refrigerator through the drain port 14.
In the conventional constitution, however, the surface temperature of the glass tube of the defrosting heater 15 is always very high temperature. Further, the bottom plate 17 is located near the defrosting heater 15, and part of the heat rays radiated from the defrosting heater 15 are reflected again to the defrosting heater 15, and hence the glass tube temperature rises abnormally high, possibly exceeding the ignition point of the flammable refrigerant.
Hence, when the flammable refrigerant is used, it is an important problem that the defrosting heater 15 should never be source of ignition due to supply of power even if the flammable refrigerant should leak out from the evaporator or the piping installed in the portion communicating with the inside of the refrigerator.